echo the no-string errors to stderr and return 1.

Fix output on launch

Drop __fish_urlencode.fish

Drop prompt_pwd.fish

share/functions/__fish_urlencode.fish

@@ -1,8 +1,4 @@
 function __fish_urlencode --description "URL-encode stdin"
-	if not type -q string
-		return 1
-	end
-	
 	set -l join ''
 	set -l chars
 	# Set locale to C and IFS to "" in order to split a line into bytes.

share/functions/prompt_pwd.fish

@@ -5,12 +5,6 @@ function prompt_pwd --description "Print the current working directory, shortene
 			return 0
 	end
 
-	# If we don't have a string builtin, we have no hope of maniuplating $PWD - just output it as-is.
-	if not type -q string
-		echo $PWD
-		return 0
-	end
-
 	# This allows overriding fish_prompt_pwd_dir_length from the outside (global or universal) without leaking it
 	set -q fish_prompt_pwd_dir_length; or set -l fish_prompt_pwd_dir_length 1
 

share/functions/string.fish

@@ -3,14 +3,16 @@ if not contains string (builtin -n)
 		if not set -q __is_launched_without_string
 			if status --is-interactive
 				# We've been autoloaded after fish < 2.3.0 upgraded to >= 2.3.1 - no string builtin
-				set_color --bold
-				echo "Fish has been upgraded, and the scripts on your system are not compatible"
-				echo "with this prior instance of fish. You can probably run:"
-				set_color green
-				echo "\n exec fish"
-				set_color normal
-				echo "… to replace this process with a new one in-place."
+				set_color --bold >&2
+				echo "Fish has been upgraded, and the scripts on your system are not compatible" >&2
+				echo "with this prior instance of fish. You can probably run:" >&2
+				set_color green >&2
+				echo -e "\n exec fish" >&2
+				set_color normal >&2
+				echo "… to replace this process with a new one in-place." >&2
+				set -g __is_launched_without_string 1
 			end
 	    end
+	    return 127
 	end                                                                  
 end